CA2904951A1 - Turbine ring for a turbomachine - Google Patents

Abstract

Turbomachine turbine ring, in particular for helicopters, whose vibratory behavior is reduced. According to the invention, this turbine ring comprises a support (31), essentially cylindrical, and one or more sectors (32) forming a ring configured to materialize a section of an air stream, each sector (32) being fixed on the support (31) by a device attachment (33a, 33b), in which the attachment device (33a) comprises a hook part (35) belonging to the support (31) and protruding towards the sector (32), and a hook part (34) belonging to sector (32) and projecting in the direction of the holder (31), the hook parts of the holder (34) and the sector (35) being configured to cooperate to secure the sector (32) on the support (31), the ring further comprising a device damping (50) provided within the attachment device (33a) and radially constrained between a portion of the sector (34e) and a portion of the support (31i) so as to cushion the relative movements of the sector (32) with respect to the support (31).

Description

TURBINE RING FOR TURBOMACHINE
FIELD OF THE INVENTION
This paper relates to a turbine ring of turbomachine, especially for helicopter.
Such a ring can be used for any type of turbomachine so to reduce the vibratory behaviors that may appear within such rings.
STATE OF THE PRIOR ART
In a typical helicopter turbomachine, the rings of high pressure turbine usually include a crown of sectors fixed on a ring support. As is visible on the FIG 2, the sectors have for this purpose hooks capable of cooperating with bracket hooks.
In contact with the air stream, the ring sectors are subject to solicitation of the aerodynamic flow, caused in particular by the wake upstream and downstream stages, and can thus behave vibratory. In particular, in the operating range of the engine, the sectors are likely to resonate, a phenomenon that may lead to cracking due to vibratory fatigue or premature wear phenomena.
To date, in order to better control such behaviors vibratory, a way of improvement is to rework the geometry even sectors. However, ad hoc geometry design is complex due to mechanical and aerodynamic constraints imposed.
Another known solution, easier to implement, consists of to reduce the games in the assembly of the rings. However, the tightening between the sectors and the support causes mechanical stress the fixing hooks which can therefore to know important plastic deformations, even cracks.
In addition, such an operation complicates the mounting procedure of rings, thereby increasing the cost of production and maintenance.

2 There is therefore a real need for a turbine ring, and a turbomachine, which are lacking, at least in part, disadvantages inherent in the aforementioned known configurations.
PRESENTATION OF THE INVENTION
The present disclosure relates to a turbine ring comprising a support, essentially cylindrical, and one or more sectors forming a ring configured to materialize a section of air stream, each sector being fixed on the support by an attachment device, wherein the hooking device comprises a hook portion belonging to the support and projecting towards the sector, and a hook part belonging to the sector and projecting towards the support, the bracket and sector hook portions being configured to cooperate in order to fix the sector on the support; the ring includes, in addition, a damping device provided within the device hooking and constrains radially between a portion of the sector and a portion of the support so as to dampen the relative movements of the sector in relation to the support; the damping device is in contact alternately in the circumferential direction with the surface internal support and the outer surface of the hook portion of the sector.
So thanks to this damping device that keeps at least a zone of pressure on said portion of the sector and at least one zone pressure on said portion of the support, the relative movements of the sector and support are constrained and therefore less important. In addition, they are quickly damped by friction of the sector and / or the support against the damping device. These friction dissipating the energy sectors, it no longer accumulates, which reduces the risk of resonances of sectors over the operating range and so limit strongly the damages by vibratory fatigue.
In addition, thanks to this damping device which forces elastic way the relative movements of the sector and the support, it is possible to maintain a radial clearance between the sector and the sufficient support to limit the mechanical stress of the fatigue type oligocyclic practicing on the sector and the support, thus prolonging their life.
This damping device also makes it possible to release the sector of its secondary objective of limiting vibrations. From then on, his WO 2014/14049

3 geometry can be chosen more freely: it can thus be simplified, resulting in cost reductions, or optimized more effectively at other functions of the sector.
In addition, this damping device allows an assembly ease of the sector on the support by acting as a guide whose radial dimension corresponds substantially to the game to separate the support sector: the sector can therefore be tacked against the device cushioning to ensure accurate positioning. We obtain increased positioning accuracy and repeatability, resulting in especially a better mastery of the game at the top of dawn and reducing machining non-conformities.
Such a configuration in which the damping device is in contact alternately, in the circumferential direction, with the inner surface of the support and the outer surface of the hook portion of the sector ensures a simple shaping of the damping device, this the latter does not have to ensure permanent and simultaneous contact with the inner surface of the support and the outer surface of the hook portion of the sector.
In some embodiments, the damping device is further configured to flatten a portion of the sector against a portion of the support. Therefore, the relative movements of the sector and the support can also be cushioned by friction of the sector against the support.
In some embodiments, the support is also attached through a second hooking device similar to the first attachment device; it is also equipped with a second damping device provided in the second device hooking, similar to the first damping device.
In some embodiments, the damping device includes a flexible blade. Preferably, this flexible blade is a sheet metal element. Such a flexible sheet is inexpensive, easy to put into shape, and has a stiffness adapted to such damping.
In some embodiments, the damping device is constrained radially between said portion of the sector and said portion support over its entire length. Therefore, the constraints on the

4 sector and support are spread over the entire length of the sector. In In addition, depreciation is homogeneous across the sector.
In some embodiments, the damping device is substantially smooth over its entire length with the exception of localized recesses distributed along its length. It may include spherical impressions made by stamping for example.
In other embodiments, the device comprises a corrugated iron element.
In some embodiments, the damping device is provided between an outer surface of the sector hook portion and an internal surface of the support. Such a configuration is easy to to assemble. In addition, in this configuration, the two hook parts are pressed against each other, which reinforces the fixation of the sector and its depreciation.
In other embodiments, the damping device is provided between an inner surface of the hook portion of the support and an outer surface of the sector.
In some embodiments, the damping device is housed at least partly in a groove made in a portion sector. Thanks to this groove, it is possible to mount the device of damping on the sector before its assembly on the support, this which facilitates the assembly procedure. In addition, this reduces the radial clearance between the sector and the support.
In other embodiments, the damping device is housed at least partly in a groove made in a portion of the support.
In some embodiments, the damping device envelope at least the distal portion of the hook portion of the support.
The damping device is thus easily put in place and remains in position even in the absence of the sector.
In some embodiments, the damping device is configured to maintain at least one zone permanently pressure on the outer surface of the hook portion of the support and a pressure zone on its inner surface, on the one hand, and at least one pressure zone on the inner surface of the sector hook portion and / or a pressure zone on an external surface of the sector, other go. The damping device is thus clipped around the end of the hook, which ensures its positioning and immobilization.
In other embodiments, the damping device envelopes at least the distal portion of the hook portion of the sector.

5 In some embodiments, the damping device is monoblock and continuous all along the circumference of the crown formed by the sector or sectors. It can however be interrupted by a gap formed in an azimuthal plane of the device.
In other embodiments, the damping device is divided into a plurality of successive sections all along the circumference of the crown formed by the sector or sectors.
In some embodiments, a section of the device amortization is associated with each sector.
In other embodiments, each section of the device damping is associated with a plurality of sectors.
In some embodiments, the damping device is configured to further ensure a seal between the support and the sector. It may be for example a braided seal.
In some embodiments, the damping device is attached to either the sector or the support. This solidarity is preferably performed by welding.
This presentation also relates to a turbomachine comprising at least one ring according to any one of aforementioned realization.
In some embodiments, the turbomachine is a helicopter turbine engine. Said ring equips the linked turbine and / or the free turbine.
In some embodiments, the turbomachine is a aircraft turbojet engine.
The aforementioned features and advantages, as well as others, will appear on reading the detailed description that follows, examples of realization of the ring and the proposed turbomachine. This description detail refers to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS

6 The attached drawings are schematic and are intended primarily to illustrate the principles of the invention.
In these drawings, from one figure (FIG) to the other, elements (or element parts) are identified by the same signs of reference. In addition, elements (or parts of elements) belonging to different embodiments but having a similar function are identified in the figures by incremented numerical references 100, 200, etc.
FIG 1 is an overview of an example of a turbine engine helicopter.
FIG 2 is a broken perspective view of a first example of a turbine ring.
FIG 3 is an axial sectional view of the ring of FIG 2.
FIG 4 illustrates a variant of the ring of FIG 2.
FIG 5 is a cutaway perspective view of another variant of the ring of FIG 2.
FIG 6A illustrates an alternative damping device.
FIG 6B is a radial sectional view of the ring of FIG.
provided with the damping device of FIG. 6A.
FIG 7A illustrates another variant of damping device.
FIG 7B is a radial sectional view of the ring of FIG.
provided with the damping device of FIG 7A.
FIG 8A is an axial sectional view of a second example ring.
FIGS. 8B and 8C are views in axial section of variants of the ring of FIG 8A.
FIG 9 is an axial sectional view of a third example ring.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
In order to make the invention more concrete, examples of turbine are described in detail below, with reference to the accompanying drawings.
It is recalled that the invention is not limited to these examples.
FIG 1 illustrates a turbomachine 10, in this case a turbine engine helicopter. In a conventional manner, this turbine engine 10 comprises a compressor 11, a gas generator 12 and linked turbines 13 and free

7 14, also called high pressure turbine and low pressure turbine, rotated by the flow of burnt gases leaving the chamber of The free turbine 14 comprises a turbine wheel 14a which is attached to one end of a shaft 15. At the other end of the shaft 15 is a primary pinion 16 which meshes with a pinion intermediate 17. This intermediate gear 17 meshes meanwhile with a output gear 18. Intermediate gear 17 and output gear 18 are gear wheels that are part of the speed reducer of the turbomachine 10. The output gear 18 is connected to an output shaft 19 intended to be coupled to the main gearbox of the helicopter (not shown here). The linked turbine 13, comprising a turbine wheel 13a is connected to the compressor 11 by via a motor shaft 20. The linked turbine 13 is furthermore equipped with a turbine ring 30 which materializes the vein of air vis-à-screw blades of the turbine wheel 13a.
FIG 2 illustrates a first example of such a turbine ring 30.
This comprises a generally cylindrical ring support 31, integral part of the casing of the turbine 13, and a crown of ring sectors 32 fixed on the ring support 31 so as to materialize the air stream of the turbine 13.
As best seen in FIG 3, each sector ring 32 is fixed on the ring support 31 by means of fastening means 33a and 33b: in each attachment device 33a, 33b, a hook 34 of the sector 32 extends towards the support 31 to cooperate with a hook 35 of the support 31 extending towards the ring sector 32.
hooks 34 of the sector 32 thus have a radial portion 34a and a tangential portion 34b and extend continuously throughout each sector 32. The hooks 35 of the support 31 also have a radial portion 35a and a tangential portion 35b and extend circumferentially continuously all along the circumference of the support 31.
In this first embodiment, the hooks 34 of the sector 32 are provided with a rib 41 protruding from the outer surface 34e hook 34 in the extension, at least partially, of the portion radial 34a of the hook 34. This rib 41 allows to play a game

8 radial between the outer surface 34e of the hook 34 and the inner surface 31i support 31 to set up a damper 50.
This damper 50 is a flexible blade, preferably a sheet metallic, taking substantially the shape of a V in this section plane axial: this sectional shape is substantially constant over the entire length of the damper 50. The damper 50 is thus forced between the outer surface 34 of the hook 34 of the sector 32 and the inner surface 31i of the support 31 in such a way that it exerts, on the one hand, a pressure on the hook 34 by its central zone and, on the other hand, a pressure on the support 31 by its two ends.
The stiffness of this damper 50 can be adjusted by regulating the thickness, the length and more generally the shape of the damper. In particular, in this example, the damper is made using a sheet metal about 0.2mm thick. Its material can also be chosen in depending on the desired stiffness. In this case, this sheet is a plate in Inconel 718.
As can be seen in FIG. 2, in this example, the damper 50 of each attachment device 33a, 33b is monobloc and continuous all along the ring support 31 with the exception of a hyphenation in an azimuthal plane of the damper 50 so as to facilitate its implementation.
place in the turbine 13. However, in other examples, the damper could be continuous all the way along the ring holder without have hyphenation.
Many variants of this first embodiment are possible. For example, in the variant of FIG 4, a groove 42 is dug into the outer surface 34 of the hook 34 of the ring sector 32. Such a groove 42 can accommodate the damper 52. The depth of this groove 42 is nevertheless smaller than the height of the damper 52 so that the damper 52 protrudes above the external surface 34 of the hook 34: the damper 52 is therefore constrained between the support 31 and the hook 34 of the sector 32.
In addition, FIG 4 illustrates that it is also possible to mount the damper 52 in a head-to-tail position relative to that of the damper 50 of FIG 3: therefore, the damper 52 exerts a pressing on the inner surface 31i of the support 31 by its central zone

9 while it exerts a pressure on the hook 34 of the sector 32 by its two ends.
FIG. 5 illustrates another variant of the first example of embodiment of the ring 30. In this variant, the damper 54 is not monobloc but sectorized: in this case, the divisions of the shock absorber 54 are planned to correspond to the sector divisions ring 32 such that a damper section 54 is associated with 32. However, it goes without saying that the damper 54 could to be divided otherwise.
FIGS. 6A and 6B illustrate yet another variant of the first example of turbine ring 30. Unlike the example of FIG 3, the damper 56 is not here shaped along its entire length. Indeed, in this variant, the damper 56 is a flexible blade, preferably a metal sheet, substantially smooth over its entire length except recesses 57 made regularly in its smooth surface.
As can be seen in FIG. 6B, the damper 56 is configured so that its outer surface bears against the surface internal 31i of the ring support 31 while the inner end of these recesses 57 rest against the outer surface 33e of the hook 33 of the ring sector 32 so that the damping device 56 is in contact alternately, in the circumferential direction, with the inner surface 31i of the support 31 and the external surface 33e of the hook 33 of the ring sector 32.
FIGS. 7A and 7B illustrate a last variant of the first example of the turbine ring 30. In this variant, the damper 58 is a corrugated sheet whose oscillations allow the damper 58 to be in contact alternately, in the circumferential direction, with the inner surface 31i of the support 31 and the outer surface 34e of the hook 33 ring sector 32.
FIG 8A illustrates a second example of a turbine ring 130.
In this second example, the damper 160 is a flexible blade of preferably a metal sheet, substantially in the shape of a U
in this plane of axial torque, engaged around the distal portion of the hook 135 of the support 131, that is to say at the end of the portion tangential 135b of the hook 135. The damper 160 thus comprises a flat portion 161, pressed against the distal surface of the hook 135, which extend the two branches of the damper 160. In a first portion 162, the two branches are tightened so as to enclose the distal portion of the hook 135 then, in a second portion 163, the two branches deviate so as to come to rely on the 5 surface internal 134i of the tangential portion 134b of the hook 134 of a part, and on the outer surface 132e of the ring sector 132 on the other hand.
In this example, the two branches of the damper 160 are symmetrical.
FIG 8B illustrates a variant of the second exemplary ring of turbine 130. In this variant, in order to obtain a different stiffness, the

10 internal branch of the shock absorber 160 is longer than its branch external. Thus, the second portion 163 of the inner branch is based on the outer surface 132e of the ring sector 132 further downstream than in the example of FIG 8A.
FIG. 8C illustrates another variant of the second example In this variant, the internal branch of the damper 160 has a first constricted portion 162 which rests against the internal surface 135i of the hook 135 but does not have no second portion resting against the outer surface 132e of the ring sector 132.
FIG 9 illustrates a third example of a turbine ring 230.
In this third example, the damper 260 is a flexible blade of preferably a metal sheet substantially in the form of an L in this axial cutting plane, engaged around the distal portion of the hook 234 of the ring sector 232. The shock absorber 260 includes a portion 261, pressed against the radial portion 235a of the hook 235 of the ring support 231, from which extends a branch generally tangential. In a first portion 262, this branch is tightening inwards so as to rest against the outer surface 234th of the hook 234 of the sector 232, then in a second portion 263, this branch moves outward so as to come to rely on the 231i internal surface of the support 231. Finally, this branch folds radially inwards so as to bear at right angles to the outer surface 234e of the hook 234. The hook portion 234 of the sector 232 is thus pressed against the hook portion 235 of the support 231.
The modes or examples of embodiment described herein presentation are given by way of illustration and not limitation, a person from

11 profession can easily, in view of this presentation, modify these modes or examples of realization, or to envisage others, while remaining in the scope of the invention.
In particular, all the examples of embodiment described relate to the linked turbomachine turbine but these lessons can also apply to the free turbine. Similarly, these lessons are transpose directly to the field of aircraft turbojets.
In addition, the different characteristics of these modes or examples embodiments can be used alone or be combined with each other.
When combined, these characteristics can be as described above or differently, the invention is not limited to specific combinations described in this paper. In particular, unless otherwise specified, a feature described in connection with a mode or example of embodiment can be applied in a similar manner to another mode or embodiment.

Claims (10)

12 1. Turbine ring comprising a support (31), essentially cylindrical, and one or more sectors (32) forming a ring configured to materialize a section of air vein, each sector (32) being fixed on the support (31) by an attachment device (33a, 33b), wherein the hooking device (33a) comprises a portion of hook (35) belonging to the support (31) and projecting towards the sector (32), and a hook portion (34) belonging to the sector (32) and projecting towards the support (31), the hook portions of the medium (34) and the sector (35) being configured to cooperate in order to fixing the sector (32) on the support (31), characterized in that it further comprises a device damping element (50) provided in the attachment device (33a) and radially constrained between a portion of the sector (34th) and a portion of the support (31i) so as to dampen the relative movements of the sector (32) relative to the support (31), and in that the damping device (56) is in contact alternatively, in the circumferential direction, with the inner surface the support (31) and the outer surface of the sector hook portion (32). Ring according to claim 1, characterized in that the damping device comprises a flexible blade (50), preferably a sheet metal element. Ring according to claim 1 or 2, characterized in that the damping device (50) is constrained radially between said portion of the sector (34e) and said portion of the support (31i) over its entire length. Ring according to any one of claims 1 to 3, characterized in that the damping device (50) is provided between an outer surface (34e) of the hook portion (34) of the sector (32) and an inner surface (311) of the support (31). Ring according to any one of claims 1 to 4, characterized in that the damping device (52) is housed at least partly in a groove (42) made in a portion (34e) of sector (32). Ring according to one of claims 1 to 3, characterized in that the damping device (160) encloses the minus the distal portion of the hook portion (135) of the support (131). Ring according to Claim 6, characterized in that the damping device (160) is configured to maintain permanence at least one pressure zone on the outer surface of the hook portion (135) of the support (131) and a pressure zone on its inner surface, on the one hand, and at least one pressure zone on the internal surface (134i) of the hook portion (134) of the sector (132) and / or a pressure zone on an outer surface (132e) of the sector (132), on the other hand. 8. Ring according to any one of claims 1 to 3, characterized in that the damping device (260) encloses the minus the distal portion of the hook portion (234) of the sector (232). Ring according to any one of claims 1 to 8, characterized in that the damping device (54) is divided into one plurality of sections succeeding each other all along the circumference of the crown formed by the sector or sectors (32), a section being preference associated with each sector (32). 10. Turbomachine comprising at least one ring (30) according to any one of the preceding claims.